1. Field of the Invention
The present invention relates to motorcycle mileage counters and, more specifically, to a motorcycle mileage inductor, which accurately detects the amount of rotation of the motorcycle's front wheel.
2. Description of the Related Art
There are two types of motorcycle mileage counters, i.e., the mechanical type and the electronic type. A mechanical type mileage counter uses a gear set for rotating a cable upon rotation of the motorcycle's front wheel, causing the mileage counter to count the number of turns. An electronic mileage counter uses an electronic device as sensor means to detect the amount of rotation of the motorcycle's front wheel and to provide a signal indicative of the amount of rotation of the motorcycle's front wheel to the internal circuit of the electronic mileage counter, which is in turn converts the signal into data for display. Either of mechanical type or electronic type, a motorcycle has installed therein a particular specification gear set or program. When changed the front wheel with a different model, the gear set or program may not fit the specification of the new front wheel perfectly, and a counting error will occur under this situation.
U.S. Pat. No. 5,880,585 shows a rotation detector for two-wheel vehicle. As shown in FIGS. 5 and 6, a plurality of elements 52 are mounted in a hole 51 at a wheel hub 5; a collar 62 is mounted in a housing 6 for the passing of a shaft 622; a magnetic rotor 7 mounted on the outer portion 621 of the collar 62; lugs 71 arranged at the outer end of the magnetic rotor 7 and fit the gaps 521 in between the elements 52; a circuit board 8 is mounted at an insertion portion 61 of the housing 6 and has installed therein a sensor 81. During movement of the two-wheel vehicle, the magnetic rotor 7 is rotated with the hub 5, and the sensor (magnetic conversion element) 81 detects changes in magnetic poles of the magnet, which changes are indicative of rotational displacement by the wheel.
The aforesaid prior art design of rotation detector has numerous drawbacks as follows:
1. The magnetic rotor 7 is directly fastened to the outer portion 621 of the collar 62. During high-speed rotation of the magnetic rotor 7, a friction is produced between the periphery of the hole 72 and the outer portion 621 of the collar 62, and the mechanism will wear quickly with use.
2. Because the magnetic rotor 7 is directly fastened to the outer portion 621 of the collar 62, the gap between the periphery of the hole 72 and the outer portion 621 of the collar 62 must be accurately designed, and the related processing precision is critical.
3. In order to reduce friction between the magnetic rotor 7 and the collar 62, a gap must be left between the hole 72 and the outer portion 621 of the collar 62, however the gap may lower the accuracy of the detection.
4. After matching of the lugs 71 of the magnetic rotor 7 with the gaps 521 in between the elements 52, a clearance will be left between each lug 71 and the two opposite sides of the respective gap 521, such a clearance may cause the magnetic rotor 7 not to be synchronously moved with the wheel, resulting an inaccuracy of the reading of the mileage counter or the action of the ABS (anti-locking braking system) of the two-wheel vehicle.